The invention relates to an automatic servo-mechanism for a sequential gearbox and clutch, in other words a combination of hydraulic and electric devices that enable servo-assisted control of the clutch when a sequential gearbox is used, thus safeguarding all possible manual operations, but allowing the level of servo-assistance to be adjusted at will.
The prior art already includes actuator devices for sequential gearboxes that consist of hydraulic cylinders in which the pressure on the hydraulic cylinders changes the gear up or down, in sequence.
The prior art also includes mechanical actuators for the control of the clutch in motorcycles in which the mechanical control actuates a lever, which, by means of a sprocket-rack drive, shifts the clutch disk; the return to the original position is achieved by the clutch springs themselves. A manual hydraulic control is also used that consists of an actuator comprising a single-stroke hydraulic cylinder that acts on the clutch rod disk and which is controlled by a pump that is connected to the user""s manual control lever.
The need for both manual and servo-assisted and possibly automatic dual operation is particularly keenly felt in racing and supertouring vehicles. In fact, in motorcycle applications dual operation of both the gear and the clutch is a very important safety factor.
With remote control of the gearbox, the control that actuates the sequential gearbox must at the same time actuate the clutch in order to operate correctly, therefore the familiar clutch actuator, in other words the aforementioned lever with sprocket and rod with rack, or the manual hydraulic control system with single-stroke cylinder, must be remote controlled.
These requirements are met by Italian patent application M099A000025 by the inventor of this servo-mechanism, in which an actuator for the remote control of the clutch and an actuator for the gearbox are described; both actuators can be used separately or jointly in this servo-mechanism. In addition, the considerable power that is today used in motorcycle engines in particular requires the user to make a considerable effort to actuate the clutch, it is therefore extremely tiring to frequently actuate the clutch, as is necessary in racing or super tourism.
There is considerable scope for perfecting this prior art in terms of eliminating the disadvantages described above in order to enable the user to control at will the level of servo-assistance required, and to achieve complete automation.
The foregoing discussion shows that it is necessary to solve the technical problem of devising a servo-mechanism that adapts to the user""s requirements, can be implemented at a later date, keeps manual operation completely straightforward, and is easy for even the user to fit onto the vehicle.
The invention solves the aforementioned technical problem by adopting: an automatic servo-mechanism for sequential gearbox and clutch, which is fitted or which can be fitted to a motorised vehicle, consisting of a sequential gearbox, a hydraulic circuit and an actuator that controls the clutch, which actuator is actuated by a solenoid valve, characterised therein that it consists of: a selector that regulates the analog electric signal that controls the solenoid valve; a microswitch on the lever that actuates the clutch mechanically; the hydraulic circuit also contains at least one check valve downstream of the pump; at least one pneumatic-hydraulic accumulator, connected downstream of the aforementioned check valve; the aforementioned proportional solenoid valve that regulates the pressure in the controlled section that is connected to the aforementioned actuator according to the analog signal received.
Adopting, in a preferred embodiment, the aforementioned selector, which regulates the analog electric signal, which signal can be set at any point on a scale from zero to the maximum value.
Adopting, in a second preferred embodiment, an electronic control unit, the input signals of which at least are connected to the aforementioned regulation selector, the control unit""s output signals at least being connected to the aforementioned solenoid valve with outlet pressure that is proportionate to the analog electric control signal.
Adopting, in another preferred embodiment, a gear sensor, which is coupled mechanically to the selector drum of the sequential gearbox and is connected by means of its own output signal to the inputs of the aforementioned control unit.
Adopting, in another preferred embodiment, a clutch rod position sensor, which is coupled mechanically to the aforementioned clutch actuator and is connected by means of its own output signal to the inputs of the aforementioned control unit.
Adopting, in another preferred embodiment, a vehicle-speed sensor, coupled mechanically to the vehicle wheels and connected by means of its own output signal to the inputs of the aforementioned control unit.
Adopting, in another embodiment, a hydraulic-circuit pressure sensor, a sensor that monitors the position of the power control and a sensor that monitors the engine""s revolutions per minute; each of the aforementioned sensors being connected by means of its own output signal to the inputs of the aforementioned control unit.
Adopting, in another preferred embodiment, the aforementioned control unit that is connected to control a device that temporarily cuts off the power generated by the engine, which device may be of any type that is suitable for the engine used.
Also adopting, in another embodiment, a gear change-intention sensor, which is connected between the gear lever and the frame, in order to monitor the gear actuation intention.
Also adopting, in another embodiment, the aforementioned gear change-intention sensor between the gear lever and the frame, which also monitors the direction of the gear change, for changing the gear up or down.
Finally adopting, in another preferred embodiment, an actuator for sequential gear changing, which actuates the gear lever without the user""s intervening.
The following advantages are obtained by this invention: the electrohydraulic servo-mechanism enables the clutch to be controlled independently of its constitution, the user can in fact use the selector to set the intervention level and can choose completely manual, completely automatic or any intermediate position; in addition, the presence of the sensor on the sequential gearbox rod enables automatic operation to be combined with total servo-assistance if the user actuates the gearbox, or partial servo-assistance to be used if the user uses the clutch lever to override the automatic operation of the sensor on the gearbox rod.
In addition, the use of the electronic control unit, with its capacity to monitor a large number of parameters, enables further levels of automatic operation to be achieved, which enable clutch intervention to be adjusted during gear changing whereas otherwise the user has to control the clutch by reducing vehicle performance through sharp braking and swift gear changing.